Tentative fix for T57066: Daily build of Blend 2.79 crashes on OSX Mojave.

Looks like we need to explicitly set i18n language to default value on
some OSs... Unless that 'need to create new translated-name IDs in
versionning code for startup file' situation is really seldom.

Anyway, hopefully that will fix the crash.

source/blender/windowmanager/intern/wm_init_exit.c

@@ -188,7 +188,10 @@ void WM_init(bContext *C, int argc, const char **argv)
 	ED_node_init_butfuncs();
 
 	BLF_init(); /* Please update source/gamengine/GamePlayer/GPG_ghost.cpp if you change this */
+
 	BLT_lang_init();
+	/* Must call first before doing any .blend file reading, since versionning code may create new IDs... See T57066. */
+	BLT_lang_set(NULL);
 
 	/* reports cant be initialized before the wm,
 	 * but keep before file reading, since that may report errors */
@@ -197,6 +200,7 @@ void WM_init(bContext *C, int argc, const char **argv)
 	/* get the default database, plus a wm */
 	wm_homefile_read(C, NULL, G.factory_startup, false, true, NULL, WM_init_state_app_template_get());
 
+	/* Call again to set from userpreferences... */
 	BLT_lang_set(NULL);
 
 	if (!G.background) {